Don’t allow test messages to be scheduled

For two reasons:
- it’s extra stuff in tour that users dont yet need to know about
- test messages are hidden from the dashboard, so you’d have no
  visibility of when they were sending once you’d scheduled them

app/templates/views/check.html

@@ -145,10 +145,12 @@
     <form method="post" enctype="multipart/form-data" action="{{url_for('main.start_job', service_id=current_service.id, upload_id=upload_id)}}" class='page-footer'>
       <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
       <input type="hidden" name="help" value="{{ '3' if help else 0 }}" />
-      {{ radio_select(
-        choose_time_form.scheduled_for,
-        wrapping_class='bottom-gutter-2-3'
-      ) }}
+      {% if choose_time_form %}
+        {{ radio_select(
+          choose_time_form.scheduled_for,
+          wrapping_class='bottom-gutter-2-3'
+        ) }}
+      {% endif %}
       <input type="submit" class="button" value="Send {{ count_of_recipients }} {{ message_count_label(count_of_recipients, template.template_type, suffix='') }}" />
       <a href="{{ back_link }}" class="page-footer-back-link">Back</a>
     </form>